docs: def change_view(self, request, object_id, form_url='', extra_context=None):
          """The ``change`` admin view for the
          :class:`Page <pages.models.Page>`."""
          language = get_language_from_request(request)
          extra_context = {
              'language': language,
              'page_languages': settings.PAGE_LANGUAGES,
          }
          try:
              int(object_id)
          except ValueError:
              raise Http404('The "%s" part of the location is invalid.'
                  % str(object_id))
          try:
              obj = self.model.objects.get(pk=object_id)
          except self.model.DoesNotExist:
              # Don't raise Http404 just yet, because we haven't checked
              # permissions yet. We don't want an unauthenticated user to be able
              # to determine whether a given object exists.
              obj = None
          else:
              template = get_template_from_request(request, obj)
              extra_context['placeholders'] = get_placeholders(template)
              extra_context['traduction_languages'] = [l for l in
                  settings.PAGE_LANGUAGES if Content.objects.get_content(obj,
                                      l[0], "title") and l[0] != language]
          extra_context['page'] = obj
  
          response = super(PageAdmin, self).change_view(request, object_id,
              form_url=form_url, extra_context=extra_context)
          if request.method == 'POST' and isinstance(response, HttpResponseRedirect):
              if '_continue' in request.POST or '_saveasnew' in request.POST or '_addanother' in request.POST:
                  addlanguage = True
              else:
                  addlanguage = False
              if addlanguage:
                  splitted = list(urllib.parse.urlparse(response.url))
                  query = urllib.parse.parse_qs(splitted[4])
                  query['language'] = language
                  splitted[4] = urllib.parse.urlencode(query)
                  response = HttpResponseRedirect(urllib.parse.urlunparse(splitted))
          return response